Cross-flow fluid machine having counterrotating rotors



N LAING 3,150,315

CROSS-FLOW FLUID MACHINE HAVING COUNTERRO'I'ATING ROTORS Sept. 29, 1964 2 Sheets-Sheet 1 Filed Sept. 5, 1962 INVENTOR olous Loin Nik ATTORNEYS Sept. 29, 1964 N. LAING 3,150,316

CROSS-FLOW FLUID MACHINE HAVING COUNTERROTATING ROTORS Filed Sept. 5, 1962 2 Sheets-Sheet 2 2 g INVENTOR Nikolaus Loing ATTORNEYS United States Patent 3,156,816 CRUSd-FLOW FLUED MACHTNE HAVING (IGUNTERROTATKNG ROTQRS Nikolaus Laing, liosenhergstrasse 24A, tuttgarn Germany Filed Sept. 5, 1952, Ser. No. 221,618 7 Claims. (Cl. 23047) This invention relates to a cross-flow fluid type machine for inducing movement of fluid which term is to be understood as comprising both liquids and gases and this application is a continuation-in-part of application Serial No. 671,114 filed July 7, 1957, now abandoned.

The invention relates more particularly to a flow machine oi the cross-flow type having a plurality of bladed cylindrical rotors arranged side-by-side with their axes parallel and having means co-operating with the rotors to guide fluid th ough the rotors and at least twice through the path of he rotating blades in a direction transverse to the axis of the rotors.

Various means are disclosed in copending application Serial No. 671,114, now abandoned, for guiding fluid through the rotor of a cross-flow machine wherein the fluid wfll pass from a suction side of the rotor through the path of the rotating blades to the interior of the rotor and thence through the path of the rotating blades to the pressure or delivery side of the rotor. Among the means disclosed are guide means which form, with a rotor of the type described, a fluid vortex approximating a Rankine type vortex having a core eccentric with the rotor axis and interpenetrating the path of the rotating blades. The velocity profile of the flow taken in a plane perpendicular to the flow within the rotor or at the pressure side oi the machine having the vortex is uneven with the profile having pronounced maximum and minimum points. The maximum point is in that part of the flow which passes closest to the core of the vortex as explained in the copending application. This uneven characteristic of the velocity profile is utilized to improve efficiency of cross-flow type machines when operated under low Reyn olds number conditions as further explained in the copending application.

In some instances it is desirable that the velocity profile at the pressure side of a cross-flow machine be even or rectangular shaped when the flow maclu'ne has two or more rotors. it is therefore an object of the invention to provide for a cross-flow type machine having a plurality of rotors wherein the velocity profile of flow at the pressure or delivery side or" the machine will be substantially rectangular in shape.

It is further desirable in some applications where flow type rotors are positioned with their axes parallel, that a maximum amount of fluid pass through the machine. it is therefore a further object of the invention to provide or a cross flow machine having parallel rotors wherein the flow of fluid through each of the rotors of the machine in turn induces flow of additional fluid through the machine in order to increase the over-all throughput.

The invention also contemplates utilizing the flow issuing from one rotor of a cross-flow machine having a plurality of rotors to act as a guide wall for the flow issuing from another rotor thereby avoiding inclusion of separate guide walls to guide the fluid which in turn results in increase of efliciency of the machine because of the decrease in skin friction that would be attendant with the guide walls.

Broadly, a flow machine constructed according to the invention comprises two counterrotating hollow cylindrical bladed rotors positioned with their axes parallel to each other and vortex formers extending the length of the rotors associated with each of the rotors whereby fluid vortexes are formed having fields approximating that of Rankine type vortexes. The core of each vortex formed is eccentric with a rotor axis whereby fluid will pass from a suction side of a rotor through the path of the rotating blades into the interior of the rotor and thence out of the rotor through the path of the rotating blades to a pressure side and the flow at the pressure side of all rotors is in tae same general direction.

In addition, the fluid machine may include guide wall members extending the length of each rotor to define entry regions to the fluid machine and to control passage of induced lluid flow through the machine.

Referring to the drawings in which preferred embodiments of the invention are diagrammatically illustrated,

FIG. 1 is a cross-sectional view of a fluid machine having guide wall means to regulate induced fluid flow through the machine;

FiG. 2 is a cross-sectional view of a machine similar to FIG. 1 with the exception that the guide wall means are joined to prevent induced fluid flow through the machine, and

FIG. 3 is a cross-sectional view of a machine similar to FIG. 1 with the exception that no guide wall means are utilized to control induced fluid flow through the machine.

Referring to the drawings in which like parts have the same identifying numerals the machine 1 of FIG. 1, includes two similar hollow cylindrical counterrotating bladed rotors 2 and 3 mounted for rotation about adjacent parallel axes with their direction of rotation being indicated by the arrows 4 and 5. The rotors 2 and 3 have associated therewith vortex-forming means 6 and 7 comprising bodies which define with the rotor gaps 8 and 9 converging in the direction of rotation of the rotors.

Each of the rotors of the machine shown in FIG. 1 has associated therewith guide walls 10 and lit which in combination with the vortex forming means 6 and 7 form an entry region therebetween. The vortex forming means 6 and '7 along with end walls 12, only one of which is shown, form a common exit duct 14 for the fluid flow machine having side walls 15. The guide wall members have a radius of curvature which increases monotonically in the direction of rotation from the point of nearest approach.

As explained in copending application Ser. No. 671,114, now abandoned the gaps 8 and 9 will form vertexes having a core V which will extend the length of the rotor and which when the rotor is rotated, cause the fluid to flow along flow lines F from the suction side S of each rotor through the path of the rotating blades to the interior of the rotor and thence through the path of the rotating blades to a pressure side P of each rotor. Also as explained in the copending application, the flow tube of maximum velocity occurs as the flow tube MF adjacent the periphery of the core V where the flow tube is deflected approximately This in turn results in the greater amount of fluid passing through each rotor where the velocity in the rotor is high and a lesser amount passing through where the velocity is low. Further the velocity of the flow at the pressure side P will likewise be uneven such that a velocity profile of the flow taken in a plane perpendicular to the direction of fiow of a single rotor will have a pronounced peak with the greater velocity occurring near the core of a vortex and along a wall 15 of the duct 14.

In order that the velocity profile in the duct 14 might be made more even or rectangular shaped to reduce mixing losses, the rotors and vortex forming means are positioned symmetrically about the centerline 16 of the machine with the result that the flow line and vortexes are likewise positioned symmetrically about the centerline. The effect of this arrangement is to make the fiow issuing from one rotor act as a guide wall for the flow issuing from the other rotor thus avoiding the need for the physical presence of separate guide walls for each flow so that the arrangement avoids skin friction which occurs with the presence of a guide wall. If a guide wall were present the attendant skin friction would effect the slowest or middle stream tubes the most thus accentuating the peaky nature of the velocity profile taken in the duct 14. The construction of a machine such as shown in PEG. 1 minimizes the peaky profile and enables the profile at the outlet of the machine to be more rectangular thus reducing excessive mixing losses due to variance in velocity. The fluid issuing from each rotor may be utilized to induce still further flow through the gap 18 formed by the guide walls and i1 and end walls thus increasing overall throughput of the machine.

In some constructions it may be undesirable to have further flow induced through the machine. In this event, the gap 18 may be closed by having the guide members 10' and 11' extend to meet along the centerline of the machine as shown in FIG. 2.

The construction in FIG. 3 illustrates a machine utilizing only the vortex formers 6 and '7 for guiding flow from the suction to the pressure sides of the rotors. This construction depends upon the principle that the major throughput of each of the rotors will occur along the flow tubes MP of maximum velocity and that only minor flow occurs in the section of the rotor on the side opposite the axis from the vortex forming means. In principle, the machine shown in FIG. 3 performs in the same manner as that shown in FIG. 1 with the exception that there are no positive guide means It and 11 to define entry regions to the rotors and a gap to serve as an entry region for the induced flow through the machine.

While only one vortex forming means has been disclosed, it is to be understood that other vortex forming means may be utilized following the disclosures of the copending application Serial No. 671,114, now abandoned.

I claim:

1. A fluid flow machine having two hollow cylindrical bladed rotors arranged with their axes parallel and for counterrotation with respect to each other, and a vortex forming means associated with each said rotor extending the length of said rotor for forming a fluid vortex when said machine is operated having a core eccentric with the axis of the rotor with which it is associated turd penetrating the blade envelope of the rotor with which it is associated to define a suction and pressure side of said rotor; the vortex forming means of both said rotors together forming side walls of a single exit duct for said flow machine, the suction sides of said rotors facing oppositely away from one another and the pressure sides of said rotors facing towards said exit duct whereby fluid will flow through the path of the rotating blades into each said rotor from the suction side thereof and thence out through the path of the rotating blades to the pressure side thereof with the flow of the rotors being in the same general direction through the exit duct.

2. A fluid flow machine according to claim 1 having guide wall means associated with each said rotor and defining with said vortex forming means an entry region for flow of fluid into each rotor; the guide wall means of both said rotors positioned apart to form a gap whereby fluid will be induced to flow by the fluid passing through the rotors through said gap to the pressure side of the machine.

3. A fluid flow machine according to claim 1 wherein each said rotor has associated therewith guide wall means curving away from the rotor in the direction of 4 rotation and defining with the vortex forming means an entry region for entry of fluid into said rotor; the guide wall means of each said rotor joining at the centerline of said machine.

4. A fluid flow machine having at least two parallel counterrotating hollow cylindrical bladed rotors of equal length, means for substantially covering the end of said rotors, and vortex forming means associated with each said rotor extending the length of said rotors for forming fluid vortexes when said machine is operated with the vortex forming means of both said rotors and means covering the end of said rotors together defining a single exit duct for said flow machine; each said vortex having a core interpenetrating the blade envelope of a single rotor whereby fluid will flow from a suction side of the rotor through the path of the rotating blades into the rotor and thence out of the rotor through the path of the rotating blades to a pressure side of the rotor with the flow at the pressure side of boh rotors being substantially in the same direction.

5. A fluid flow machine according to claim 4 wherein said rotors and vortex forming means are spaced symmetrically about a centerline of said machine to form a gap in said machine whereby additional fluid is induced to flow through said gap by the fluid passing through said rotors to increase the overall throughput of said machine.

6. A fluid flow machine comprising a pair of similar hollow bladed cylindrical rotors arranged with their axes parallel and for counterrotaation with respect to each other, a pair of vortex forming means extending the length of the rotors and symmetrically arranged with respect thereto with a portion of each said vortex forming means extending away from a rotor to form a side wall of a single exit duct for said machine, and guide wall means extending the length of the rotors opposite the vortex forming means and also symmetrically disposed with respect thereto with the guide wall means and vortex forming means defining a pair of oppositely disposed entry openings with each said opening leading to one rotor; said vortex formers when said rotors are rotated each forming with one rotor a fluid vortex having a core eccentric with the rotor axis and penetrating the blade envelope of the rotor whereby fluid will flow through the path of the rotating blades from the corresponding entry opening into the interior of the rotor and thence out the path of the rotating blades to the exit duct with the flow from both rotors in said exit duct having substantial mirror symmetry about a central plane.

7. A fluid flow machine having at least two parallel counterrotating hollow cylindrical bladed rotors of equal length, and vortex forming means associated with each said rotor extending the length of the rotor and forming fluid vortexes when said machine is operated with said vortex forming means of .each rotor providing a guide surface adjacent each rotor extending into a side wall of a single exit duct for said machine; each said vortex having a core interpenetrating the blade envelope of a single rotor whereby fluid will flow from a suction side of the rotor through the path of the rotating blades into the rotor and thence out of the rotor through the path of the rotating blades to a pressure side of the rotor with the flow at the pressure side of both rotors being substantially in the same direction.

References Cited in the file of this patent UNITED STATES PATENTS 848,343 Brown et al Mar. 26, 1907 2,634,048 McDonald Apr. 7, 1953 2,942,773 Eek June 28, 1960 

1. A FLUID FLOW MACHINE HAVING TWO HOLLOW CYLINDRICAL BLADED ROTORS ARRANGED WITH THEIR AXES PARALLEL AND FOR COUNTERROTATION WITH RESPECT TO EACH OTHER, AND A VORTEX FORMING MEANS ASSOCIATED WITH EACH SAID ROTOR EXTENDING THE LENGTH OF SAID ROTOR FOR FORMING A FLUID VORTEX WHEN SAID MACHINE IS OPERATED HAVING A CORE ECCENTRIC WITH THE AXIS OF THE ROTOR WITH WHICH IT IS ASSOCIATED AND PENETRATING THE BLADE ENVELOPE OF THE ROTOR WITH WHICH IT IS ASSOCIATED TO DEFINE A SUCTION AND PRESSURE SIDE OF SAID ROTOR; THE VORTEX FORMING MEANS OF BOTH SAID ROTORS TOGETHER FORMING SIDE WALLS OF A SINGLE EXIT DUCT FOR SAID FLOW MACHINE, THE SUCTION SIDES OF SAID ROTORS FACING OPPOSITELY AWAY FROM ONE ANOTHER AND THE PRESSURE SIDES OF SAID ROTORS FACING TOWARDS SAID EXIT DUCT WHEREBY FLUID WILL FLOW THROUGH THE PATH OF THE ROTATING BLADES INTO EACH SAID ROTOR FROM THE SUCTION SIDE THEREOF AND THENCE OUT THROUGH THE PATH OF THE ROTATING BLADES TO THE PRESSURE SIDE THEREOF WITH THE FLOW OF THE ROTORS BEING IN THE SAME GENERAL DIRECTION THROUGH THE EXIT DUCT. 